Clutch



Patented Feb. 7, 1939 UNITED STATES PATENT OFFICE CLUTCH William S. Wolfram, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich a corporation of Delaware This invention relates to friction clutches such as areused to couple the engine and transmission shafts of motor vehicles.

An object 'of the invention is to supplement 3 the normal clutch engaging instrumentality with mechanism acting automatically to increase the gripping action between the driving and driven members.

A further object is to accomplish'the above D major object with a degree of efliciency varying with the tendency of the driving and driven members to'slip relative to each other and eifective to correct said tendency in either direction of rotation.

I Associated with the above objects is an arrangement permitting the use of a lighter spring for the reason that its yielding action in effecting clutch engagement is supplemented by a servo device. Other objects and advantages will be un- D derstood from the following description.

In the accompanying drawing:

Figure 1 is a transverse section through the novel clutch, the section corresponding to line l-l of Figure 2.

I Figure 2 is a view in elevation facing the cover plate Figure 3 is a section on line 3-3 of Figure 2.

Figures 4 and 5 are similar sections but with the parts displaced from the positions they ocll' cupy in Figure 3.

Referring by reference characters to the drawing, numeral I is used to designate the engine shaft and 9 the clutch driven shaft or transmission shaft. At H are shown fastening means 5 which secure a flywheel I3 to the engine shaft. To the flywheel is secured a cover l5 by means of fastening devices II. A pressure plate l9 within the cover is mounted to reciprocate axially relative to the flywheel and to grip a driven plate 2| 0 having facings 23 between itself and the flywheel. The driven plate is associated with a hub 25 splined on the driven shaft 3, and between the hub 25 and the driven plate is cushioning spring means 21 such as is commonly employed. The

5 p essure plate is formed with a plurality of axial lugs 23 extending through arcuate openings 3| in the cover. Cap screws 33 are threaded into the lugs and may engage washers 35 as shown. This last described arrangement provides for the pressure plate a limited rotary as well as axial movement. I

The pressure plate may be actuated to clutch engaging position by some known form of spring. There is shown a coned spring plate 31 to serve 5 this purpose. At its outer periphery it engages the pressure plate at 33. A plurality of shouldered rivets ll arranged in a circular series are carried by the cover l5. Two rings 43 and 45 are positioned axially of the clutch by these rivets. The spring plate 31 has a circular series of open- 6 ings so that it may be located on the rivets between the rings. Radially inward from the rivets the coned spring 31 is formed with slots 41, and its inner margin is secured to a collar 49 by an assembly for which no invention is here claimed 10 but which is designated as a whole by numeral 5|.

The spring plate normally exerts pressure on the pressure plate, moving it to the left in Figure 1, and the reaction is taken by the ring 45. When the collar 43 is moved to the left by the II conventional clutch fork, only the ends 53 of which are shown, the load is taken from the ring 45 and assumed by the collar. The reciprocation of the collar then serves together with the fulcrum ring 43 to release the pressure plate from the spring pressure.

One or more resilient plate members 55 are used to positively withdraw the pressure plate when the clutch is released. One end of each 'member 55 may be anchored by a rivet 4| and the other end may be received within a notch of the pressure plate.

A plurality of radial recesses 51 are formed on the pressure plate, each recess having sloping surfaces GI and 63. These recesses are on the side of the pressure plate facing the cover plate. Opposite the pressure plate recesses are similar V-shaped radial recesses 65 on the cover plate and between the mating recesses are tapered rollers 61 normally lying in the deep parts of the recesses. When the spring 31 is permitted to move the pressure plate in contact with the driven plate and thereby to push the latter against the flywheel, the pressure plate has a limited rotation relative to the flywheel and cover owing to the freedom of movement of the lugs 29 in the arcuate recesses 3|. Such relative rotation causes a movement of the rollers 61 from the position shown in Figure 4 to that of either Fig- 5 ure 3 or Figure 5 depending upon whether the flywheel overruns the driven plate or the driven plate overruns the flywheel. In either event the pressure plate is moved axially away from the cover and thereby is more firmly pressed against the driven plate. There is thus added to the action of spring 31 an effective servo action tending to more effectively grip the driven plate. This makes possible the use of a relatively light clutch engaging spring and therefore one which can'be more easily overcome by the releasing action 01 the throwout mechanism.

I claim:

1. In a clutch, a driving member, a pressure plate reciprocable axially relative to said driving member cooperating means on said driving member and pressure plate to permit and provide a limited relative movement of rotation, a driven member between said driving member and pressure plate, yielding means operable to move said and pressure plate to move said pressure plate towards said flywheel, and other means responsive to said relative rotation to urge said pressure plate towards said flywheel.

3. The invention defined by claim 2, said other means comprising opposed V-shaped recesses in said cover and pressure plate and rollers in said I recesses.

4. The invention defined by claim 2, said other means comprising opposed radially directed vshaped recesses in said cover and pressure plate and rollers in said recesses.

5. In a clutch for motor vehicles, a flywheel, a cover secured thereto to form an enclosure, a pressure plate axially reciprocable within said enclosure, a driven shaft extending into said enclosure and having a driven plate secured thereto and positioned between said flywheel and pressure plate, said pressure plate having axial lugs and said cover having elongated arcuate slots to receive said lugs'whereby said pressure plate may have a limited rotary movement relative thereto, yielding means between said cover and pressure plate to move the latter to clutch engaging posisure plate to be moved toward said driven plate therebysupplementing the action of said yielding means.

WILLIAM S. WOLFRAM. 

